Plaid Server

A self-hosted MCP server that lets Claude query your bank accounts, balances, and transactions through Plaid.

Tools

Tool	Description
accounts	All linked bank accounts
balances	Current/available balances and credit limits
transactions	Full transaction history for a date range
total_spending	Total spending broken down by category
transactions_by_category	Filter transactions by Plaid PFC category
merchants	All merchants for a date range, sorted by total spend
transactions_by_merchant	Filter transactions by merchant name

How it works

• OAuth 2.1 + PKCE with Google as the identity provider
• Email allowlist is the security boundary
• Claude.ai gets a 30-day bearer token; your Plaid access token never leaves your server
• Caddy sits in front of FastAPI, terminating TLS on port 443 with auto-provisioned Let's Encrypt certs and reverse-proxying to localhost:8080

Requirements

• A Linux server with a public IP (this guide uses an AWS EC2 t3.micro)
• A domain name pointing at it (this guide uses a free DuckDNS subdomain)
• A Plaid developer account with production access
• A Google Cloud account for the OAuth client

Setup

1. Plaid

1. Create a Plaid account at dashboard.plaid.com
2. Request Production access in the dashboard (Plaid will review your application — this can take a few days)
3. Once approved, save your client_id and Production secret from Team Settings → Keys

2. Google OAuth

1. console.cloud.google.com → create a project
2. APIs & Services → OAuth consent screen → set up an "External" app, add yourself as a test user
3. APIs & Services → Credentials → Create credentials → OAuth client ID
4. Application type: Web application
5. Authorized redirect URIs: https://yourdomain.com/auth/google/callback (use your real domain from step 4 below)
6. Save the Client ID and Client secret

3. Server

This guide assumes AWS EC2:

1. Launch a t3.micro Ubuntu 24.04 instance
2. Security group: inbound TCP 22 (SSH from your IP), 80, 443
3. Allocate an Elastic IP and associate it with the instance
4. SSH in: ssh -i your-key.pem ubuntu@<elastic-ip>

4. Domain

Free option using DuckDNS:

1. Sign in with Google/GitHub/Reddit
2. Reserve a subdomain (e.g. plaid-yourname)
3. Set the IP to your Elastic IP
4. Your domain is now plaid-yourname.duckdns.org

Go back to step 2.5 and set the redirect URI to https://plaid-yourname.duckdns.org/auth/google/callback.

5. Install

On the server:

git clone https://github.com/lukew0824/plaid-mcp.git
cd plaid-mcp
cp .env.example .env
nano .env   # fill in everything
./install.sh

The script:

• Installs Python, Caddy, and dependencies
• Sets up and starts a systemd service (plaid-mcp) that auto-restarts on failure and boot
• Configures Caddy as a reverse proxy with auto-HTTPS via Let's Encrypt

6. Connect in Claude.ai

1. Claude.ai → Settings → Connectors → Add custom connector
2. URL: https://yourdomain.com/mcp
3. Click Connect
4. Sign in with the Google account matching ALLOWED_EMAIL
5. First time only: a Plaid Link popup will appear — connect your bank
6. Done. Try: "What did I spend on food last month?"

Configuration

The .env values:

Key	Description
PLAID_ENV	production
PLAID_CLIENT_ID	From Plaid dashboard
PLAID_PRODUCTION_SECRET	From Plaid dashboard
GOOGLE_CLIENT_ID	From Google Cloud Console
GOOGLE_CLIENT_SECRET	From Google Cloud Console
ALLOWED_EMAIL	The single Google email allowed to authenticate
BASE_URL	Public HTTPS URL of this server (no trailing slash)
DATABASE_URL	sqlite:///./plaid_mcp.db (default works for self-hosting)

License

MIT